chore(package): update prettier to version 2.0.5

Closes #51

Author: greenkeeper[bot]

package.json

@@ -39,7 +39,7 @@
     "tsyringe": "^4.0.1"
   },
   "devDependencies": {
-    "prettier": "^1.15.3",
+    "prettier": "^2.0.5",
     "tslint": "^5.12.0",
     "tslint-config-prettier": "^1.17.0",
     "tslint-config-standard": "^9.0.0",